1
|
Choi S, Kronstad JW, Jung WH. Siderophore Biosynthesis and Transport Systems in Model and Pathogenic Fungi. J Microbiol Biotechnol 2024; 34:1551-1562. [PMID: 38881181 PMCID: PMC11380514 DOI: 10.4014/jmb.2405.05020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/05/2024] [Accepted: 06/10/2024] [Indexed: 06/18/2024]
Abstract
Fungi employ diverse mechanisms for iron uptake to ensure proliferation and survival in iron-limited environments. Siderophores are secondary metabolite small molecules with a high affinity specifically for ferric iron; these molecules play an essential role in iron acquisition in fungi and significantly influence fungal physiology and virulence. Fungal siderophores, which are primarily hydroxamate types, are synthesized via non-ribosomal peptide synthetases (NRPS) or NRPS-independent pathways. Following synthesis, siderophores are excreted, chelate iron, and are transported into the cell by specific cell membrane transporters. In several human pathogenic fungi, siderophores are pivotal for virulence, as inhibition of their synthesis or transport significantly reduces disease in murine models of infection. This review briefly highlights siderophore biosynthesis and transport mechanisms in fungal pathogens as well the model fungi Saccharomyces cerevisiae and Schizosaccharomyces pombe. Understanding siderophore biosynthesis and transport in pathogenic fungi provides valuable insights into fungal biology and illuminates potential therapeutic targets for combating fungal infections.
Collapse
Affiliation(s)
- Sohyeong Choi
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
| | - James W Kronstad
- Michael Smith Laboratories, Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
| |
Collapse
|
2
|
Wang Y, Wang B, Gao Y, Nakanishi H, Gao XD, Li Z. Highly efficient expression and secretion of human lysozyme using multiple strategies in Pichia pastoris. Biotechnol J 2023; 18:e2300259. [PMID: 37470505 DOI: 10.1002/biot.202300259] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/11/2023] [Accepted: 07/17/2023] [Indexed: 07/21/2023]
Abstract
BACKGROUND Human lysozyme (hLYZ), an emerging antibacterial agent, has extensive application in the food and pharmaceutical industries. However, the source of hLYZ is particularly limited. RESULTS To achieve highly efficient expression and secretion of hLYZ in Pichia pastoris, multiple strategies including G418 sulfate screening, signal sequence optimization, vacuolar sorting receptor VPS10 disruption, and chaperones/transcription factors co-expression were applied. The maximal enzyme activity of extracellular hLYZ in a shaking flask was 81,600 ± 5230 U mL-1 , which was about five times of original strain. To further reduce the cost, the optimal medium RDMY was developed and the highest hLYZ activity reached 352,000 ± 16,696.5 U mL-1 in a 5 L fermenter. CONCLUSION This research provides a very useful and cost-effective approach for the hLYZ production in P. pastoris and can also be applied to the production of other recombinant proteins.
Collapse
Affiliation(s)
- Yasen Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China
| | - Buqing Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China
| | - Yahui Gao
- School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Hideki Nakanishi
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Zijie Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, School of Biotechnology, Ministry of Education, Jiangnan University, Wuxi, Jiangsu, China
| |
Collapse
|
3
|
Stanford FA, Matthies N, Cseresnyés Z, Figge MT, Hassan MIA, Voigt K. Expression Patterns in Reductive Iron Assimilation and Functional Consequences during Phagocytosis of Lichtheimia corymbifera, an Emerging Cause of Mucormycosis. J Fungi (Basel) 2021; 7:jof7040272. [PMID: 33916756 PMCID: PMC8065604 DOI: 10.3390/jof7040272] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/17/2021] [Accepted: 03/29/2021] [Indexed: 12/30/2022] Open
Abstract
Iron is an essential micronutrient for most organisms and fungi are no exception. Iron uptake by fungi is facilitated by receptor-mediated internalization of siderophores, heme and reductive iron assimilation (RIA). The RIA employs three protein groups: (i) the ferric reductases (Fre5 proteins), (ii) the multicopper ferroxidases (Fet3) and (iii) the high-affinity iron permeases (Ftr1). Phenotyping under different iron concentrations revealed detrimental effects on spore swelling and hyphal formation under iron depletion, but yeast-like morphology under iron excess. Since access to iron is limited during pathogenesis, pathogens are placed under stress due to nutrient limitations. To combat this, gene duplication and differential gene expression of key iron uptake genes are utilized to acquire iron against the deleterious effects of iron depletion. In the genome of the human pathogenic fungus L. corymbifera, three, four and three copies were identified for FRE5, FTR1 and FET3 genes, respectively. As in other fungi, FET3 and FTR1 are syntenic and co-expressed in L. corymbifera. Expression of FRE5, FTR1 and FET3 genes is highly up-regulated during iron limitation (Fe-), but lower during iron excess (Fe+). Fe- dependent upregulation of gene expression takes place in LcFRE5 II and III, LcFTR1 I and II, as well as LcFET3 I and II suggesting a functional role in pathogenesis. The syntenic LcFTR1 I–LcFET3 I gene pair is co-expressed during germination, whereas LcFTR1 II- LcFET3 II is co-expressed during hyphal proliferation. LcFTR1 I, II and IV were overexpressed in Saccharomyces cerevisiae to represent high and moderate expression of intracellular transport of Fe3+, respectively. Challenge of macrophages with the yeast mutants revealed no obvious role for LcFTR1 I, but possible functions of LcFTR1 II and IVs in recognition by macrophages. RIA expression pattern was used for a new model of interaction between L. corymbifera and macrophages.
Collapse
Affiliation(s)
- Felicia Adelina Stanford
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research, and Infection Biology—Hans Knöll Institute (HKI), 07745 Jena, Germany; (F.A.S.); (N.M.); (M.I.A.H.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany;
| | - Nina Matthies
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research, and Infection Biology—Hans Knöll Institute (HKI), 07745 Jena, Germany; (F.A.S.); (N.M.); (M.I.A.H.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany;
| | - Zoltán Cseresnyés
- Applied Systems Biology, Leibniz Institute for Natural Product Research, and Infection Biology—Hans Knöll Institute, 12622 Jena, Germany;
| | - Marc Thilo Figge
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany;
- Applied Systems Biology, Leibniz Institute for Natural Product Research, and Infection Biology—Hans Knöll Institute, 12622 Jena, Germany;
| | - Mohamed I. Abdelwahab Hassan
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research, and Infection Biology—Hans Knöll Institute (HKI), 07745 Jena, Germany; (F.A.S.); (N.M.); (M.I.A.H.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany;
- National Research Centre, Pests & Plant Protection Department, 33rd El Buhouth St., Dokki, Giza 12622, Egypt
| | - Kerstin Voigt
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research, and Infection Biology—Hans Knöll Institute (HKI), 07745 Jena, Germany; (F.A.S.); (N.M.); (M.I.A.H.)
- Institute of Microbiology, Friedrich Schiller University Jena, 07743 Jena, Germany;
- Correspondence: or ; Tel.: +49-3641-532-1395
| |
Collapse
|
4
|
Stanford FA, Voigt K. Iron Assimilation during Emerging Infections Caused by Opportunistic Fungi with emphasis on Mucorales and the Development of Antifungal Resistance. Genes (Basel) 2020; 11:genes11111296. [PMID: 33143139 PMCID: PMC7693903 DOI: 10.3390/genes11111296] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/23/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023] Open
Abstract
Iron is a key transition metal required by most microorganisms and is prominently utilised in the transfer of electrons during metabolic reactions. The acquisition of iron is essential and becomes a crucial pathogenic event for opportunistic fungi. Iron is not readily available in the natural environment as it exists in its insoluble ferric form, i.e., in oxides and hydroxides. During infection, the host iron is bound to proteins such as transferrin, ferritin, and haemoglobin. As such, access to iron is one of the major hurdles that fungal pathogens must overcome in an immunocompromised host. Thus, these opportunistic fungi utilise three major iron acquisition systems to overcome this limiting factor for growth and proliferation. To date, numerous iron acquisition pathways have been fully characterised, with key components of these systems having major roles in virulence. Most recently, proteins involved in these pathways have been linked to the development of antifungal resistance. Here, we provide a detailed review of our current knowledge of iron acquisition in opportunistic fungi, and the role iron may have on the development of resistance to antifungals with emphasis on species of the fungal basal lineage order Mucorales, the causative agents of mucormycosis.
Collapse
Affiliation(s)
- Felicia Adelina Stanford
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research, and Infection Biology–Hans Knöll Institute, Jena, Adolf-Reichwein-Straße 23, 07745 Jena, Germany;
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich-Schiller University Jena, Neugasse 25, 07743 Jena, Germany
| | - Kerstin Voigt
- Jena Microbial Resource Collection, Leibniz Institute for Natural Product Research, and Infection Biology–Hans Knöll Institute, Jena, Adolf-Reichwein-Straße 23, 07745 Jena, Germany;
- Institute of Microbiology, Faculty of Biological Sciences, Friedrich-Schiller University Jena, Neugasse 25, 07743 Jena, Germany
- Leibniz Institute for Natural Product Research and Infection Biology–Hans Knöll Institute, Jena Microbial Resource Collection Adolf-Reichwein-Straße 23, 07745 Jena, Germany
- Correspondence: ; Tel.: +49-3641-532-1395; Fax: +49-3641-532-2395
| |
Collapse
|
5
|
Martínez-Pastor MT, Puig S. Adaptation to iron deficiency in human pathogenic fungi. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118797. [PMID: 32663505 DOI: 10.1016/j.bbamcr.2020.118797] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/13/2020] [Accepted: 07/05/2020] [Indexed: 02/08/2023]
Abstract
Iron is an essential micronutrient for virtually all eukaryotic organisms and plays a central role during microbial infections. Invasive fungal diseases are associated with strikingly high rates of mortality, but their impact on human health is usually underestimated. Upon a fungal infection, hosts restrict iron availability in order to limit the growth and virulence of the pathogen. Here, we use two model yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe, to delve into the response to iron deficiency of human fungal pathogens, such as Candida glabrata, Candida albicans, Aspergillus fumigatus and Cryptococcus neoformans. Fungi possess common and species-specific mechanisms to acquire iron and to control the response to iron limitation. Upon iron scarcity, fungi activate a wide range of elegant strategies to capture and import exogenous iron, mobilize iron from intracellular stores, and modulate their metabolism to economize and prioritize iron utilization. Hence, iron homeostasis genes represent remarkable virulence factors that can be used as targets for the development of novel antifungal treatments.
Collapse
Affiliation(s)
| | - Sergi Puig
- Departamento de Biotecnología, Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Paterna, Valencia, Spain.
| |
Collapse
|
6
|
Makni M, Jemai R, Kriaa W, Chtourou Y, Fetoui H. Citrus limon from Tunisia: Phytochemical and Physicochemical Properties and Biological Activities. BIOMED RESEARCH INTERNATIONAL 2018; 2018:6251546. [PMID: 29568760 PMCID: PMC5820557 DOI: 10.1155/2018/6251546] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/27/2017] [Accepted: 12/06/2017] [Indexed: 01/19/2023]
Abstract
Natural plant extracts contain a variety of phenolic compounds which are assigned various biological activities. Our work aims to make a quantitative and qualitative characterization of the Zest (ZL) and the Flesh (FL) of lemon (Citrus limon), to valorize the pharmacological uses of lemon, by evaluating in vitro activities (DPPH, free radical scavenging and reducing power). The antibacterial, antifungal, and antiproliferative activities were sought in the ability of Citrus limon extracts to protect DNA and protein. We found that the ZL contains high amounts of phenolics responsible for the important antioxidant properties of the extract. However, the FL is richer in flavonoids than the ZL. The FL extract was also found to be more effective than the ZL in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals. We also concluded that the FL extract exhibited potent antibacterial activity unlike ZL. Analysis by LC/MS-MS identified 6 compounds (Caffeoyl N-Tryptophan, Hydroxycinnamoyl-Oglucoside acid, Vicenin 2, Eriocitrin, Kaempferol-3-O- rutinoside, and Quercetin-3-rutinoside). These preliminary results showed that Citrus limon has antibacterial and antioxidant activity in vitro. It would be interesting to conduct further studies to evaluate the in vivo potential in an animal model.
Collapse
Affiliation(s)
- Mohamed Makni
- Laboratory of Toxicology, Environmental Microbiology and Health, Science Faculty of Sfax, University of Sfax, Sfax, Tunisia
| | - Raoua Jemai
- Laboratory of Toxicology, Environmental Microbiology and Health, Science Faculty of Sfax, University of Sfax, Sfax, Tunisia
| | - Walid Kriaa
- Laboratory of Plant Biotechnology, Faculty of Sciences of Sfax, University of Sfax, Sfax, Tunisia
| | - Yassine Chtourou
- Laboratory of Toxicology, Environmental Microbiology and Health, Science Faculty of Sfax, University of Sfax, Sfax, Tunisia
| | - Hamadi Fetoui
- Laboratory of Toxicology, Environmental Microbiology and Health, Science Faculty of Sfax, University of Sfax, Sfax, Tunisia
| |
Collapse
|
7
|
Abstract
The devastating infections that fungal pathogens cause in humans are underappreciated relative to viral, bacterial and parasitic diseases. In recent years, the contributions to virulence of reductive iron uptake, siderophore-mediated uptake and heme acquisition have been identified in the best studied and most life-threatening fungal pathogens: Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus. In particular, exciting new work illustrates the importance of iron acquisition from heme and hemoglobin in the virulence of pathogenic yeasts. However, the challenge of establishing how these fungi gain access to hemoglobin in blood and to other sources of heme remains to be fully addressed. Recent studies are also expanding our knowledge of iron uptake in less-well studied fungal pathogens, including dimorphic fungi where new information reveals an integration of iron acquisition with morphogenesis and cell-surface properties for adhesion to host cells. Overall, the accumulating information provides opportunities to exploit iron acquisition for antifungal therapy, and new work highlights the development of specific inhibitors of siderophore biosynthesis and metal chelators for therapeutic use alone or in conjunction with existing antifungal drugs. It is clear that iron-related therapies will need to be customized for specific diseases because the emerging view is that fungal pathogens use different combinations of strategies for iron acquisition in the varied niches of vertebrate hosts.
Collapse
Affiliation(s)
- Gaurav Bairwa
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - Won Hee Jung
- Department of Systems Biotechnology, Chung-Ang University, Anseong, 456-756, Republic of Korea
| | - James W Kronstad
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| |
Collapse
|
8
|
Kingsbury JM, Shamaprasad N, Billmyre RB, Heitman J, Cardenas ME. Cancer-associated isocitrate dehydrogenase mutations induce mitochondrial DNA instability. Hum Mol Genet 2016; 25:3524-3538. [PMID: 27427385 DOI: 10.1093/hmg/ddw195] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 06/16/2016] [Accepted: 06/17/2016] [Indexed: 12/15/2022] Open
Abstract
A major advance in understanding the progression and prognostic outcome of certain cancers, such as low-grade gliomas, acute myeloid leukaemia, and chondrosarcomas, has been the identification of early-occurring mutations in the NADP+-dependent isocitrate dehydrogenase genes IDH1 and IDH2 These mutations result in the production of the onco-metabolite D-2-hydroxyglutarate (2HG), thought to contribute to disease progression. To better understand the mechanisms of 2HG pathophysiology, we introduced the analogous glioma-associated mutations into the NADP+ isocitrate dehydrogenase genes (IDP1, IDP2, IDP3) in Saccharomyces cerevisiae Intriguingly, expression of the mitochondrial IDP1R148H mutant allele results in high levels of 2HG production as well as extensive mtDNA loss and respiration defects. We find no evidence for a reactive oxygen-mediated mechanism mediating this mtDNA loss. Instead, we show that 2HG production perturbs the iron sensing mechanisms as indicated by upregulation of the Aft1-controlled iron regulon and a concomitant increase in iron levels. Accordingly, iron chelation, or overexpression of a truncated AFT1 allele that dampens transcription of the iron regulon, suppresses the loss of respirative capacity. Additional suppressing factors include overexpression of the mitochondrial aldehyde dehydrogenase gene ALD5 or disruption of the retrograde response transcription factor RTG1 Furthermore, elevated α-ketoglutarate levels also suppress 2HG-mediated respiration loss; consistent with a mechanism by which 2HG contributes to mtDNA loss by acting as a toxic α-ketoglutarate analog. Our findings provide insight into the mechanisms that may contribute to 2HG oncogenicity in glioma and acute myeloid leukaemia progression, with the promise for innovative diagnostic and prognostic strategies and novel therapeutic modalities.
Collapse
Affiliation(s)
- Joanne M Kingsbury
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Nachiketha Shamaprasad
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - R Blake Billmyre
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Maria E Cardenas
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| |
Collapse
|
9
|
Kang CM, Kang S, Park YS, Yun CW. Physical interaction between Sit1 and Aft1 upregulates FOB uptake activity by inhibiting protein degradation of Sit1 in Saccharomyces cerevisiae. FEMS Yeast Res 2015; 15:fov080. [PMID: 26323600 DOI: 10.1093/femsyr/fov080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/06/2015] [Indexed: 11/15/2022] Open
Abstract
Previously, we reported that Aft1 regulates Sit1 by modulating the ubiquitination of Sit1 in Saccharomyces cerevisiae. Here, we report the function of the physical interaction between Sit1 and Aft1 in ferrioxamine B (FOB) uptake. The interaction between Sit1 and Aft1 induced protein localization of Sit1 to the plasma membrane, and more Sit1 was detected in the plasma membrane when Sit1 and Aft1 were coexpressed compared with Sit1 expression alone. The MSN5-deletion mutant, which failed to translocate Aft1 to the cytosolic compartment, showed lower FOB uptake activity than the wild type. However, higher free iron uptake activity was detected in the MSN5-deletion mutant. Furthermore, the strain transformed with AFT1-1(up) plasmid, which failed to regulate Aft1 via iron concentration and accumulated Aft1 in the nucleus, showed lower FOB uptake activity. The Aft1 Y179F mutant, which contained a tyrosine residue that was changed to phenylalanine, failed to interact physically with Sit1 and showed more degradation of the Sit1 and, ultimately, lower FOB uptake activity. Additionally, we found that MG132 and PMSF, which are inhibitors of proteasomes and serine proteases, respectively, increased the Sit1 protein level. Taken together, these results suggest that the protein-protein interaction between Sit1 and Aft1 is an important factor in the FOB uptake activity of Sit1.
Collapse
Affiliation(s)
- Chang-Min Kang
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| | - Suzie Kang
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| | - Yong-Sung Park
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| | - Cheol-Won Yun
- School of Life Sciences and Biotechnology, Korea University, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea
| |
Collapse
|
10
|
Functional genomics analysis of the Saccharomyces cerevisiae iron responsive transcription factor Aft1 reveals iron-independent functions. Genetics 2010; 185:1111-28. [PMID: 20439772 DOI: 10.1534/genetics.110.117531] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Saccharomyces cerevisiae transcription factor Aft1 is activated in iron-deficient cells to induce the expression of iron regulon genes, which coordinate the increase of iron uptake and remodel cellular metabolism to survive low-iron conditions. In addition, Aft1 has been implicated in numerous cellular processes including cell-cycle progression and chromosome stability; however, it is unclear if all cellular effects of Aft1 are mediated through iron homeostasis. To further investigate the cellular processes affected by Aft1, we identified >70 deletion mutants that are sensitive to perturbations in AFT1 levels using genome-wide synthetic lethal and synthetic dosage lethal screens. Our genetic network reveals that Aft1 affects a diverse range of cellular processes, including the RIM101 pH pathway, cell-wall stability, DNA damage, protein transport, chromosome stability, and mitochondrial function. Surprisingly, only a subset of mutants identified are sensitive to extracellular iron fluctuations or display genetic interactions with mutants of iron regulon genes AFT2 or FET3. We demonstrate that Aft1 works in parallel with the RIM101 pH pathway and the role of Aft1 in DNA damage repair is mediated by iron. In contrast, through both directed studies and microarray transcriptional profiling, we show that the role of Aft1 in chromosome maintenance and benomyl resistance is independent of its iron regulatory role, potentially through a nontranscriptional mechanism.
Collapse
|
11
|
Current awareness on yeast. Yeast 2010. [DOI: 10.1002/yea.1714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|